Since the advent of the first phonographic recordings, audio reproduction has enjoyed virtually exponential growth in quality and complexity. The increasing diversity of audio processing equipment continues to expand the technological limits on the quality of audio recording. Developments in digital recording and processing, improvements in noise reduction, and refinement of filtering techniques are just examples of the increased technological capabilities of the professional audio recording field. As these advancements take place, it becomes increasingly apparent that the role of the individuals who operate this equipment has changed. Instead of merely capturing the work of the artist, these individuals contribute in creating the sound which is actually heard by the listener.
In a typical professional recording, various artists are recorded on individual tracks in a recording studio. A complicated arrangement, such as a classical music performance, might include scores of separate tracks. As illustrated in FIG. 1, after each track has been recorded, the recorded tracks (from VTRs 1 to N) are "mixed down" to a master multitrack recording on a master VTR. The master recording can be used in a variety of ways. For example, a two channel stereo master recording may be reproduced onto phonographs, compact disks, or tapes. Alternatively, a multitrack recording may be mixed with video signals for applications in television and film.
Typically, recording, mix down and mastering are performed with a large mixer console, such as those offered by SSL and Neve. As illustrated in FIG. 1, a mixer 70 generally includes several inputs 10 that are each coupled to recorders 20 which provide the prerecorded audio tracks. Each track is assigned a separate audio channel which can be processed with individual controls. For example, the level of each channel can be faded up or down with individual fader controls, or selected frequency ranges boosted or cut.
The output of the prerecorded audio channels is coupled to a smaller number of buses. For example, these channels may be mixed together onto two buses which form stereo channels. These stereo channels can be processed in a mixer 70 and output to a master recorder 30. The mixed signals can be monitored throughout this process with monitoring devices 40. In this way, each of the audio channels are mixed together to produce a master recording.
The mixer consoles available today offer the basic feature of mixing down a relatively large number of audio channels. Additionally, they offer, to varying degrees, other capabilities intended to enhance the mastering process. For example, the SSL 4000 console includes a limiter/compressor which may be used to narrow the dynamic width of the output channels. This feature is useful in limiting the broad range of an original recording, such as a classical score, to one which is better suited to the equipment available to most consumers.
Within this basic framework, there are a seemingly endless number of peripheral devices, often referred to as "outboard equipment," which can be used to modify the sound originally recorded on the individual tracks before they reach the master recording. These devices such as the effect module 50 shown in FIG. 1, can be used to supplement or replace the processing capabilities of the mixer console, or can provide various "effects" otherwise unavailable in FIG. 1. For example, if the operator is dissatisfied with the quality of the product from the compressor on a console, a selected channel can be output from the mixer, passed through an external compressor, then returned back to the mixer console. Other devices can be used to boost or cut other selected frequencies or channels. Additional effects can be introduced in a similar manner, such as feedback and rhythmic modification of amplitude.
The mixing consoles and effects equipment available provide a vast number of combinations by which individual audio tracks can be modified during the mix down and mastering phase. Consequently, it is to be expected that the individuals responsible for this part of the recording process play an important role in creating an unique master recording, as opposed to merely reproducing the sounds of the original performers. Indeed, it is typical that given the same set of original tracks, these individuals working alone produce master recordings which are dramatically different.
While the large amount of equipment available enhances the creative aspects of mix down and mastering segments, the resulting complexity of the options available, ironically, can impede the recording process. On a basic level, the various possible combinations of effect devices encourage experimentation by the engineer. Accordingly, one is tempted to try different types of effects inserted at different points along the signal paths leading from the original individual tracks to the master output paths. However, each time a different combination is attempted, it becomes necessary to physically change the connections coupling the outboard equipment with the mix console. Thus, it becomes time consuming for the operator to try different combinations, which translates into greater total expense. It also becomes difficult for the engineer to monitor the differences between various combinations. In that these differences may be difficult to detect, an inability to quickly toggle among the combinations renders it difficult for even the experienced engineer to discern the preferred set-up. Moreover, these changes are difficult to predict, since even a familiar piece of equipment may affect the overall mix in a different manner when used in combination with other equipment.
In order to circumvent the need to change the wiring configuration each time a new combination is to be tried, it is possible to utilize extra channels on the mix console to insert the effects at different points in "submixes,"[that is combinations of input channels linked together, for example, in a daisy chain. For example, channels 1, 2, and 3, might be combined in series on the mixer to form a mixed channel input to channel 4. This might correspond to recordings of all the percussion instruments. Instead of simply combining channels 1, 2, and 3 on the master buses and then processing them along with other channels, the engineer alternatively can couple the combined submix to a compressor and return the output to channel 5 of the mixer. This permits a compressor to be used with selected channels rather than merely individual ones or the entire mix. The operator can then evaluate how the submix of channel 4 combines with the entire mix in comparison with the submix of channel 5.
While such a technique provides a partial solution to the drawbacks associated with changing wiring configurations, it is limited in several respects. For example, this technique requires channels of the mixer to be taken away for use in the standard mixing process. Another drawback is that this technique increases the overall signal path in the mix console over which the original recorded tracks travel before reaching the master record. Thus, there is a greater risk that noise present in the system will be recorded onto the master track. Moreover, it is not possible to accomplish this technique without particularly large mix consoles. For example, it is usually necessary to use a master bus which has more than two paths, such as in a video mixer. Since such consoles are expensive, they are available at only certain studios, and so the universe of locations at which the engineer can apply this technique is limited. Further, since many of the large mix consoles with which this technique may be used are not intended for high quality professional audio recording, but rather are more often used in conjunction with video applications, it is necessary to incur a certain amount of sound degradation when using such mix consoles.
The availability of a wide selection of recording equipment impedes the recording process in another, related aspect. Since the recording equipment available differs dramatically with respect to mixing consoles, it is common that mix engineers develop preferences for particular equipment based on the quality of the product and ease in use. These preferences may also arise from familiarity developed with frequent use of certain equipment. As a result, such individuals attempt to work with studios at which the preferred equipment is available. This enables the engineer to more quickly obtain the type of sound which he prefers. Consequently, the possible "matches" between the mix engineers and recording studios are reduced, thereby limiting the supply of an essential element of the recording process.
Similarly, the preferences developed by mix engineers with respect to outboard equipment may limit their experimentation with other devices. Due to the time-consuming efforts required to combine outboard equipment with other elements of the recording system, many engineers prefer to rely on the type of equipment with which they are accustomed, often bringing their own outboard equipment with them when undertaking a mix down.
In view of the foregoing, there is the need for a convenient and flexible system to expedite the initial recording, the mix down, and the mastering phases of the recording process. There is a need for a system which provides the engineer with more predictability and control. More particularly, there is a need to provide a system which can easily be combined with a wide variety of conventional mix consoles and outboard equipment so as to enable a mix engineer to more readily monitor and predict the relative improvement in sound quality offered by different set-ups. There is a further need to accomplish these requirements without introducing unwanted noise and distortion into the recording system. There is still another need to provide the foregoing in a manner which can be adapted to particular operator's preferences and which can be used with a variety of existing audio devices.